1. Goal of PC product

The objective of the PC product is to support detailed precipitation analysis for nowcasting purposes. The focus is on the delineation of non-precipitating and precipitating clouds and not on quantifying precipitation amount. Particular attention will be given to also identifying areas of light frontal precipitation.

The product provides probability results for precipitation occurance. It is not intended to provide information on the type of precipitation.

2. PC algorithm summary description

The precipitating clouds product gives the likelihood of precipitation. A linear combination of those spectral features, which have the highest correlation with precipitation, is used to construct a Precipitation index PI. For each value of the PI, the probability of precipitation in the respective classes is then determined from a comprehensive dataset of collocated satellite data, precipitation rates from surface radar and surface temperatures from NWP. Special attention has been given to spectral features in the visible, which implicitly contain information on cloud microphysical properties at the cloud top, such as optical thickness, effective radius and cloud phase. The algorithm to retrieve information on the presence of precipitation is based on the Cloud Type output. The algorithm relies much on the microphysical information available in both the 1.6 micron and 3.9 micron channels. For each algorithm a day and a night version exists. The threshold at which sun zenith angle to switch from day to night algorithm is configurable.